Transaxle including brake

ABSTRACT

A transaxle comprises a transaxle casing, axle, brake, brake arm, first and second link members, and relay arm. The brake includes a brake operation shaft pivotally supported by the transaxle casing for shifting between brake activation and inactivation states. A starting end of the first link member is connected to a manipulator, and a terminal end of the second link member is connected to the brake arm. The relay arm is pivotally centered on a first pivotal axis outside of the transaxle casing, and includes a first arm portion extended from the first pivotal axis to a first end and a second arm portion extended from the first pivotal axis to a second end. A terminal end of the first link member is connected to the first arm portion, and a starting end of the second link member is connected to the second arm portion.

BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates to a transaxle including a hydrostatictransmission (hereinafter “HST”), an axle driven by the HST, and a brakefor braking the axle. Especially, the invention relates to the transaxlethat serves as each of right and left transaxles carrying respectiveright and left axles of a zero-turn vehicle, e.g., a lawn mower.

Related Art

Conventionally, as disclosed in U.S. 2015/0007555 A1, there is awell-known hydraulic transaxle that serves as each of right and lefttransaxles carrying respective right and left axles of a zero-turnvehicle, e.g., a lawn mower. The transaxle includes an HST, an axle anda reduction gear train transmitting power from the HST to the axle. TheHST includes a hydraulic pump for receiving power from a prime mover, ahydraulic motor for outputting power to the reduction gear train, and acenter section. The hydraulic pump and motor are mounted on the centersection and are fluidly connected to each other via fluid passagesformed in the center section.

The transaxle also includes a gear-locking mechanism that includes alocking pawl serving as a parking brake for braking the reduction geartrain and the axle. The gear-locking mechanism further includes alocking shaft and a brake (locking) arm. The locking shaft is pivotallysupported by a transaxle casing of the transaxle so as to be rotatablerelative to the transaxle casing. The brake arm is fixed on a right orleft end of the locking shaft outside of the transaxle casing. Thelocking pawl is fixed on a portion of the locking shaft disposed insideof the transaxle casing. By rotating the brake arm and the lockingshaft, the locking pawl engages to any one gear of the reduction geartrain so as to stop the reduction gear train including the gear, therebystopping the axle.

In the case where the transaxle serves as each of right and lefttransaxles equipped on a vehicle, the vehicle is also equipped with abrake control mechanism including a manipulator and link membersinterposed between the manipulator and the brake arms of the respectiveright and left transaxies. Therefore, each link member moves in responseto operation of the manipulator so as to rotate the brake arm and thelocking shaft relative to the corresponding transaxle casing.

As mentioned above, either the right or left end of the locking shaft isselected to have the brake arm thereon, so that either the proximal sideor distal side of the transaxle casing of each of the transaxles in thevehicle is selected for locating the link member and the brake arm.However, it is of frequent occurrence that any member other thancomponent members of the transaxle is disposed on the proximal side ofthe transaxle casing in the vehicle. Therefore, the transaxle is desiredto be configured so as to prevent such another member disposed on theproximal side of the transaxle casing from interfering with the linkmember or the brake arm if the link member and the brake arm aredisposed on the proximal side of the transaxle casing in the vehicle.

SUMMARY OF THE INVENTION

An object of the invention is to provide a transaxle including a brake,wherein the transaxle is configured so as to prevent a brake operationmechanism operatively connected to the brake of the transaxle in avehicle from interfering with any member other than component members ofthe transaxle in the vehicle.

To achieve the object, a transaxle comprises a transaxle casing, anaxle, a brake, a brake arm, a first link member, a second link member,and a relay arm. The axle is supported by the transaxle casing. Thebrake includes a brake operation shaft pivotally supported by thetransaxle casing so as to rely on rotation of the brake operation shaftfor shifting the brake between an activation state to brake the drivetrain and an inactivation state to unbrake the drive train. The relayarm is pivotally centered on a first pivotal axis outside of thetransaxle casing. The first pivotal axis is parallel to the axis of thebrake operation shaft. The relay arm includes first and second endsopposite each other with respect to the first pivotal axis, a first armportion extended from the first pivotal axis to the first end, and asecond arm portion extended from the first pivotal axis to the secondend. A starting end of the first link member is connected to amanipulator operated for shifting the brake between the activation stateand the inactivation state. A terminal end of the first link member isconnected to the first arm portion of the relay arm. A starting end ofthe second link member is connected to the second arm portion of therelay arm. A terminal end of the second link member is connected to thebrake arm.

Therefore, the first link member, the relay arm, the second link member,and the brake arm are interposed between the manipulator and the brakeoperation shaft of the brake, so that they are located to avoid theirinterference with any obstructive member other than component members ofthe transaxle, e.g., a drive belt for driving a working device, e.g.,rotary blades of a mower unit. More specifically, if the location of thebrake arm selected to prevent such an obstructive member frominterfering with the brake arm or a link member connected to the brakearm causes a problem that the rotational direction of the brakeoperation shaft based on a movement of the link member connected to thebrake arm according to operation of the manipulator is opposite itsproper rotational direction for the brake, the relay arm advantageouslyfunctions to convert the movement direction of the first link member toanother movement direction of the second link member, thereby matchingthe rotational direction of the brake operation shaft with its properrotational direction for the brake. Further, due to the relay arm, theterminal end of the first link member is shifted by the dimension of therelay arm in comparison with the terminal end of the first link memberif it is directly connected to the brake arm, whereby this shift effectsto prevent the first link member from interfering with the obstructivemember. Therefore, the transaxle including the brake is provided with abrake control mechanism interposed between the manipulator and the brakearm outside of the transaxle, and the brake control mechanism includesthe first and second link member and the relay arm so as to be preventedfrom interfering with the obstructive member in a vehicle.

Preferably, the transaxle includes an HST disposed in the transaxlecasing. The HST includes a hydraulic pump and a hydraulic motor fluidlyconnected to each other. The hydraulic pump includes a movable swashplate having a trunnion shaft. The trunnion shaft projects outward fromthe transaxle casing so as to have the relay arm pivoted thereon so thata rotary axis of the trunnion shaft serves as the first pivotal axis.

Therefore, the existing trunnion shaft can be used to support the relayarm so that any additional member is not needed for the same purpose,thereby reducing the component members of the transaxle in number andcost, and thereby facilitating in modifying the transaxle for supportingthe relay arm.

These and other objects, features and advantages of the invention willappear more fully from the following detailed description of theinvention with reference to attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view of a lawn mower serving as a zero-turnvehicle equipped with right and left transaxles and right and leftcontrol levers for controlling the respective transaxles.

FIG. 2 is a plan view of the right transaxle serving as the transaxleaccording to the invention.

FIG. 3 is a sectional side view of the right transaxle taken alongIII-III arrows of FIG. 2.

FIG. 4 is a sectional bottom view of the right transaxle taken alongarrows of FIG. 3.

FIG. 5 is a cross sectional view taken along V-V arrows of FIG. 2.

FIG. 6 is a cross sectional view taken along VI-VI arrows of FIG. 3.

FIG. 7 is a cross sectional view taken along VII-VII arrows of FIG. 3.

FIG. 8 is an enlarged view of a principal portion of FIG. 3 showing abrake.

FIG. 9 is a left side view of the right transaxle.

FIG. 10 is a right side view partly in section of the right transaxle.

FIG. 11 is a right side view of the left transaxle.

FIG. 12 is a right side view of a speed control arm of the righttransaxle located at a neutral position.

FIG. 13 is a right side view of the speed control arm rotated from theneutral position in the direction for forward rotation of thecorresponding axle when the speed control arm reaches a predeterminedangle.

FIG. 14 is a right side view of the speed control arm rotated in thedirection for forward rotation of the corresponding axle when the speedcontrol arm reaches a maximum angle.

FIG. 15 is a right side view of the speed control arm rotated in thedirection for backward rotation of the corresponding axle when the speedcontrol arm reaches a maximum angle.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a lawn mower (hereinafter simply referred to as“vehicle”) 100 serving as a typical zero-turn vehicle is equipped withright and left transaxle 1R and 1L carrying respective right and leftaxles 2R and 21, and is equipped with right and left control levers 60Rand 60L for controlling respective right and left transaxles 1R and 1L.Hereinafter, all the descriptions will be given on an assumption thatright and left transaxles 1R and 1L are provided therebetween with acenterline disposed at the lateral middle position of vehicle 100 andextended in the fore-and-aft direction of vehicle 100, so that the sideor direction of each of transaxles 1R and 1L close to the centerline isreferred to as “proximal”, and the side or direction of each oftransaxles 1R and 1L opposite or away from the centerline is referred toas “distal”. Therefore, right transaxle 1R has its left side as itsproximal side, and has its right side as its distal side, and lefttransaxle 1L has its right side as its proximal side, and has its leftside as its distal side.

Vehicle 100 includes a vehicle body frame 4 having right and leftparallel sideboards 4 a extended in the fore-and-aft horizontaldirection thereof. Vehicle body frame 4 supports right and lefttransaxles 1R and 1L so that transaxle casings 10 of right and lefttransaxles 1R and 1L are disposed in the inside of vehicle body frame 4,i.e., between right and left sideboards 4 a when viewed in plan. Rightaxle 2R is extended rightward from transaxle casing 10 of righttransaxle 1R to the outside of right sideboard 4 a of vehicle body frame4 so as to be fixed at a distal end thereof to right drive wheel 3R.Left axle 2L is extended leftward from transaxle casing 10 of lefttransaxle 1L to the outside of left sideboard 4 a of vehicle body frame4 so as to be fixed at a distal end thereof to left drive wheel 3L.Right and left transaxles 1R and 1L are disposed in vehicle 100 so as tolaterally extend right and left axles 2R and 2L coaxially to each other.

Right and left drive wheels 3R and 3L serving as rear wheels of vehicle100 are disposed on the right and left outsides of a rear portion ofvehicle body frame 4. A front end portion of vehicle body frame 4supports castors (or castor) 5 serving as front wheels (or a frontwheel) of vehicle 100. A mower unit 6 is disposed below a fore-and-aftmiddle portion of vehicle body frame 4 between front wheels 5 and rearwheels 3R and 3L. Mower unit 6 is provided with PTO (Power Take Off)pulleys 9.

Further, vehicle 100 is equipped with an unshown prime mover, e.g., anengine, whose output power is transmitted from a double drive pulley 90of the prime mover via a belt 7 to input pulleys 14 of respective rightand left transaxles 1R and 1L. Belt 7 is looped over one pulley part ofdouble drive pulley 90 and right and left input pulleys 14, and atension pulley 91 applies a required tension onto belt 7.

Another belt 8 is looped over the other pulley part of double drivepulley 90 and PTO pulleys 9. Belt 8 is provided with a tension clutchpulley 92 adjacent to the proximal left side surface of right transaxle1R. When pulley 92 is pressed against belt 8 as drawn in solid lines inFIG. 1, pulley 92 applies a tension to belt 8 so that the rotary powerof drive pulley 90 is transmitted to PTO pulleys 9 via belt 8 so as todrive rotary blades of mower unit 6. When pulley 92 is rotated away frombelt 8 and toward right transaxle 1R as phantom lines in FIG. 1, thetension clutch serving as pulley 92 is clutched off, so that belt 8 hasno tension, whereby PTO pulleys 9 do not receive the rotary power ofdrive pulley 90 for driving the rotary blades of mower unit 6.

Transaxle casings 10 of right and left transaxles 1R and 1L incorporaterespective parking brakes 69. Therefore, to operate parking brakes 69 ofright and left transaxles 1R and 1L, vehicle 100 is provided with aparking brake control mechanism 169 that includes a parking brake pedal64 serving as a manipulator for simultaneously shifting both parkingbrakes 69 of right and left transaxles 1R and 1L between an activationstate and an inactivation state. Alternatively, the manipulator may be alever or the like. Parking brake pedal 64 is located in vehicle 100available for depression of parking brake pedal 64 by an operator'sfoot. By depressing parking brake pedal 64, both right and left drivewheels 3R and 3L are braked.

Brake control mechanism 169 includes right and left link rods 19R and19L extended rearward from parking brake pedal 64 to respectivetransaxle casings 10 of right and left transaxles 1R and 1L. When viewedin plan, right and left link rods 19R and 19L are extended in thefore-and-aft direction of vehicle 100 in the space between right andleft sideboards 4 a and between transaxle casings 10 of right and lefttransaxles 1R and 1L, i.e., on the respective proximal sides oftransaxle casings 10 of right and left transaxles 1R and 1L.Incidentally, each of right and left transaxles 1R and 1L is configuredso that one of right and left sides, i.e., proximal and distal sides, oftransaxle casing 10 is selective to have each link rod 19R or 19L. Inother words, in the embodiment shown in FIG. 1, the proximal sides oftransaxle casings 10 of right and left transaxles 1R and 1L are selectedfor arrangement of right and left link rods 19R and 19L.

Right and left link rods 18 are extended along respective right and leftsideboards 4 a rearward from respective right and left control levers60R and 60L to respective speed control arms 46 provided on distal sidesof respective transaxle casings 10 of right and left transaxles 1R and1L. When viewed in plan, right and left link rods 18 are extended in thefore-and-aft direction of vehicle 100 along respective right and leftsideboards 4 a. Incidentally, each of right and left transaxles 1R and1L is configured so that one of right and left sides, i.e., proximal anddistal sides, of transaxle casing 10 is selective to have speed controlarm 46. In other words, in the embodiment shown in FIG. 1, the distalsides of transaxle casings 10 of right and left transaxies 1R and 1L areselected for arrangement of speed control arms 46 and right and leftlink rods 18. Further, as understood from FIG. 2 illustratingrepresentative right transaxle 1R, each of right and left transaxles 1Rand 1L includes a neutral returning spring 47 on the distal side oftransaxle casing 10 with speed control arm 46.

As understood from FIG. 3 illustrating representative right transaxle1R, right control lever 60R is operable to change the tilt angle anddirection of a later-discussed movable swash plate 44 of an HST 20 ofright transaxle 1R so as to change the rotary speed and direction ofright rear wheel 3R. Left control lever 60L is operable to change thetilt angle and direction of movable swash plate 44 of HST 20 of lefttransaxle 1L so as to change the rotary speed and direction of left rearwheel 3L. When right and left control levers 60R and 60L aresynchronously manipulated by an operator, movable swash plates 44 ofHSTs 20 of right and left transaxles 1R and 1L are synchronouslycontrolled to change the straight travel speed of vehicle 100 in eitherthe forward direction or the backward direction. When right and leftcontrol levers 60R and 60L are independently manipulated, movable swashplates 44 of HSTs 20 of right and left transaxles 1R and 1L aredifferentially controlled so as to control the turn direction, angle,and speed of vehicle 100.

Referring to FIGS. 3 to 10, representative right transaxle 1R will bedescribed on an assumption that right and left transaxles 1R and 1L aresymmetric with respect to the above-mentioned laterally middlefore-and-aft centerline drawn in vehicle 100 shown in FIG. 1. Therefore,detailed description of left transaxie 1L is omitted because it isidentical or similar to right transaxle 1R, excluding a later-discusseddifference of connection of left link rod 19L to left transaxle 1L fromconnection of right link rod 19R to right transaxle 1R.

Referring to FIG. 3, right transaxle 1 includes transaxle casing 10, HST20 disposed in a front portion of transaxle casing 10, a right axle 2Rjournalled by a rear portion of transaxle casing 10, and a reductiongear train 70 disposed in the rear portion of transaxle casing 10 so asto drivingly connect HST 20 to right axle 2R.

Transaxle casing 10 includes an upper housing 11, a lower housing 12,and a top cover 13. Bolts 16 are screwed upward to fasten a flanged topedge of lower housing 12 to a bottom edge of upper housing 11 fringing abottom opening of upper housing 11. Bolts 17 are screwed downward tofasten a flanged bottom edge of top cover 13 to a top edge of a rearhalf portion of upper housing 11 fringing a top opening of the rear halfportion of upper housing 11. By joining upper housing 11 and lowerhousing 12 to each other at respective horizontal joint surfaces 11 kand 12 e thereof, a cavity of transaxle casing 10 is formed, and upperand lower housings 11 and 12 form a partition wall 10 c that divides thecavity of transaxle casing 10 into a front HST chamber 10 a and a reargear chamber 10 b.

The rear portion of upper housing 11 defining gear chamber 10 baccommodates reduction gear train 70. Top cover 13 covers an upperportion of reduction gear train 70 in gear chamber 10 b. The frontportions of upper and lower housings 11 and 12 defining HST 10 aaccommodate HST 20.

HST 20 includes a center section 30, a hydraulic pump 40, and ahydraulic motor 50. Center section 30 is entirely formed by castingintegrally with a horizontal pump port block portion 31, a slant motorport block portion 32, a bypass valve block portion 33, and a plurality(in this embodiment, four) of bolt boss portions 34 and 35. Motor portblock portion 32 is joined to pump port block portion 31 so as to extendrearwardly upward from a rear end of pump port block portion 31. Bypassvalve block portion 33 projects downward from motor port block portion32 so as to extend in the lateral horizontal portion.

As shown in FIG. 5, pump port block portion 31 is formed therein withright and left pump kidney ports 31 b and 31 c and a pump shaft hole 31d between pump kidney ports 31 b and 31 c. A horizontal pump mountingsurface 31 a is formed on a top end of pump port block portion 31. Pumpkidney ports 31 b and 31 c and pump shaft hole 31 d are extendedvertically upward so as to be open at horizontal pump mounting surface31 a.

A horizontal filter mounting surface 31 c is formed on a bottom end ofpump port block portion 31. A circumferential area of filter mountingsurface 31 e is provided to contact a top edge of a cylindrical filter26. In this regard, when HST 20 is disposed in transaxle casing 10,filter 26 contacting filter mounting surface 31 e of center section 30is submerged in a fluid sump in chamber 10 a so that fluid is filteredby filter 26 when the fluid penetrates filter 26 from the fluid sump inchamber 10 a to the inside space of filter 26.

Right and left main fluid passages 36 and 37 are formed in pump portblock portion 31 so as to extend in the horizontal fore-and-aftdirection. Referring to FIG. 3, right and left charge check valves 21are disposed in respective front portions of right and left main fluidpassages 36 and 37. Right and left suction ports 31 f are open at thebottom surface of center section 30 surrounded by filter mountingsurface 31 e. The fluid inside of filter 26 is introduced into eitherhydraulically depressed main fluid passage 36 or 37 via suction port 31f and corresponding charge check valve 21, thereby being supplied assupplementary hydraulic fluid to the closed fluid circuit of HST 20.

Referring to FIG. 4, motor port block portion 32 is formed therein withright and left motor kidney ports 32 b and 32 c and a motor shaft hole32 d between motor kidney ports 32 b and 32 c. A slant upper end ofmotor port block portion 32 is formed as a rearwardly downward slantmotor mounting surface 32 a. Right and left main fluid passages 36 and37 are extended rearward into motor port block portion 32 so as to bejoined at rear ends thereof to respective right and left motor kidneyports 32 b and 32 c.

Referring to FIG. 5, hydraulic pump 40 includes a pump shaft 41, a pumpcylinder block 42, plungers 43, and a movable swash plate 44. Pump shaft41 is fittingly passed through pump shaft hole 31 d in pump port blockportion 31 of center section 30 rotatably relative to center section 30.Pump cylinder block 42 is formed with a center through hole serving as apump shaft hole 42 a and with cylinder bores 42 b aligned radiallyaround pump shaft hole 42 a. Pump shaft 41 is fittingly passed throughpump shaft hole 42 a unrotatably relative to pump cylinder block 42.Pump cylinder block 42 is slidably rotatably fitted onto pump mountingsurface 31 a so as to fluidly connect cylinder bores 42 b therein topump kidney ports 31 b and 31 c. Plungers 43 are fitted into respectivecylinder bores 42 b reciprocally in the axial direction of pump shaft41. Movable swash plate 44 has a bearing 44 a abutting against heads ofplungers 43 projecting from pump cylinder block 42. In this way,hydraulic pump 40 is configured as an axial piston type hydraulic pump.

A front top portion of the ceiling wall of transaxle housing 11 isformed as a pump shaft support portion 11 b for supporting pump shaft41. Upper housing 11 is formed through right and left side walls of pumpsupport portion 11 b with right and left symmetric trunnion holes 11 c.Movable swash plate 44 of hydraulic pump 40 is a trunnion type movableswash plate, which is formed with right and left symmetric feet 44 bhaving respective right and left symmetric trunnion holes 44 c. Rightand left fixture pins 45 a fasten right and left feet 44 b of movableswash plate 44 to right and left trunnion shafts 45 fitted in trunnionholes 44 c.

Pump shaft support portion 11 b is formed with a vertical through holebh. An upper portion of pump shaft 41 projecting upward from pumpcylinder block 42 fitted on pump mounting surface 31 a of center section30 is freely passed through movable swash plate 44 and through verticalthrough hole bh of pump shaft support portion 11 b so as to projectupward from pump shaft support portion 11 b of transaxle housing 11. Abearing 41 a and a fluid seal 41 b are fitted in through hole bh of pumpshaft support portion 11 b so as to be interposed between pump shaft 41and pump shaft support portion 11 b of transaxle housing 11. Inputpulley 14 and a cooling fan 15 are fixed on the upper portion of pumpshaft 41 projecting upward from pump support portion 11 b of transaxlehousing 11.

Referring to FIG. 6, hydraulic motor 50 includes a motor shaft 51, amotor cylinder block 52, plungers 53, and a movable swash plate 54.Motor shaft 51 is fitted into motor shaft hole 32 d in motor port blockportion 32 of center section 30 rotatably relative to center section 30.Motor cylinder block 52 is formed with a center through hole serving asa motor shaft hole 52 a and with cylinder bores 52 b aligned radiallyaround motor shaft hole 52 a. Motor shaft 51 is fittingly passed throughmotor shaft hole 52 a unrotatably relative to motor cylinder block 52.Motor cylinder block 52 is slidably rotatably fitted onto motor mountingsurface 32 a of center section 30 so as to fluidly connect cylinderbores 52 b therein to motor kidney ports 32 b and 32 c. Cylinder bores52 b are fluidly connected to cylinder bores 42 b in pump cylinder block42 via main fluid passages 36 and 37 of the closed fluid circuit of HST20 (see FIG. 5).

Plungers 53 are fitted into respective cylinder bores 52 b reciprocallyin the axial direction of motor shaft 51. A bearing abuts against headsof plungers 53 projecting from motor cylinder block 52 so as to serve asmovable swash plate 54. In this way, hydraulic motor 50 is configured asan axial piston type hydraulic motor.

Referring to FIG. 3, a motor support member 56 is disposed in gearchamber 10 b, and is fastened to upper housing 11 by bolts 57. Movableswash plate 54 is a cradle type movable swash plate, which is rotatablyand slidably fitted to motor support member 56, and abuts against headsof plungers 53 projecting from motor cylinder block 52. Referring toFIG. 6, upper housing 11 is formed through right and left side walls ofa fore-and-aft intermediate portion thereof with right and leftsymmetric trunnion holes 11 h. Movable swash plate 54 is fixed at eithera right or left end thereof to a trunnion arm 55. A trunnion shaft 55 aprojects horizontally from trunnion arm 55 and is fitted into one ofright and left trunnion holes 11 h rotatably relative to upper housing11. Remaining trunnion hole 11 h is plugged by a cap 65.

An operation lever (not shown) is fixed on a tip portion of trunnionshaft 55 a projecting outward from transaxle casing 10. This operationlever for controlling movable swash plate 54 of hydraulic motor 50 canbe used to adjust an output scale of transaxle 1R or 1L incorrespondence to a vehicle maker's demand, or to minutely adjust theoutput performance of right and left transaxles 1R and 1L for keepingthe ability of vehicle 100 in straight traveling when control levers 60Rand 60L are operated for the straight traveling. In which directiontrunnion shaft 45 projects is selected in consideration of facility inwork for the above-mentioned output adjustment of transaxle 1R or 1L.

Right and left trunnion shafts 45 have respective tip portionsprojecting outward from the right and left side surfaces, i.e., distaland proximal side surfaces, of upper housing 11 of transaxle casing 10.Referring to FIG. 4, a speed control arm. 46 is fixed on the right tipportion of right trunnion shaft 45 projecting outward from the distalright side surface of upper housing 11 so that the tilt angle anddirection of movable swash plate 44 of hydraulic pump 40 is controlledby rotating speed control arm 46.

Neutral return spring 47 is wound around the tip portion of righttrunnion shaft 45 between speed control arm 46 and the distal right sidesurface of upper housing 11 so as to have both end portions Eu and Eltwisted to cross each other and extended rearward. A nut 46 a is screwedon the tip portion of right trunnion shaft 45 outside of speed controlarm 46 so as to prevent speed control arm 46 and neutral return spring47 from falling from right trunnion shaft 45.

Referring to FIG. 10, speed control arm 46 has a basal end portionattached on the right tip portion of right trunnion shaft 45, and has atip portion formed with a later-discussed hole 46 c into which a rearend portion of a later-discussed link rod 18 is fitted, so that speedcontrol arm 46 is extended upward from the basal end thereof to the tipend thereof. Speed control arm 46 is formed with a rear branchingportion that extends rearward from the basal end portion of speedcontrol arm 46 so as to cover front halves of end portions Eu and El ofneutral return spring 47 extended rearward from their mutual crossingportions. The rear branching portion is bent to have a rear end portionthat is extended proximally toward the distal right side surface ofupper housing 11 of transaxle casing 10 so as to serve as a pressureplate 46 b. Of both end portions Eu and El of neutral return spring 47extended rearward from their mutual crossing portions, upper end portionEu is extended at a rear half thereof above pressure plate 46 b, andlower end portion it is extended at a rear half thereof below pressureplate 46 b, so that the rear halves of upper and lower end portions Euand El of neutral return spring 47 have pressure plate 46 btherebetween. When speed control arm 46 is disposed at its neutralposition, upper and lower edges of pressure plate 46 b abut againstrespective upper and lower end portions Eu and El of neutral returnspring 47.

When pressure plate 46 b moves upward by rotating speed control arm 46,pressure plate 46 b pushes upper end portion Eu of neutral return spring47 upward. As upper end portion Eu of neutral return spring 47 pushed bypressure plate 46 b moves upward after lower end portion El of neutralreturn spring 47 abuts against an eccentric pin 49, the gap betweenupper and lower end portions Eu and El of neutral return spring 47 isexpanded so that neutral return spring 47 generates a biasing force thatbiases upper and lower end portions Eu and El toward each other.

The right side wall of upper housing 11 of transaxle casing 10adjacently rearward from right trunnion shaft 45 having speed controlarm 46 and neutral returning spring 47 thereon is firmed with aneccentric pin hole 11 d, and a laterally horizontal axis shaft 49 a ofeccentric pin 49 is fitted into eccentric pin hole 11 d. In this regard,the right and left side walls of transaxle housing 11 adjacentlyrearward from right and left trunnion holes 11 c are formed to havesufficient thickness before boring eccentric pin hole 11 d so thateither the right or left wall can be selectively bored with eccentricpin hole 11 d.

Eccentric pin 49 is fitted on a portion of axis shaft 49 a projectingoutward from transaxle housing 11 and a nut is screwed on a distal endof axis shaft 49 a so as to fasten eccentric pin 49 to axis shaft 49 a.Due to the eccentricity of eccentric pin 49 relative to axis shaft 49 a,the neutral position of speed control arm 46 defined as the positionwhere upper and lower end portions Eu and El of neutral return spring 47pinch eccentric pin 49 can be adjusted relative to the real neutralposition of movable swash plate 44 for stopping the fluid delivery fromhydraulic pump 40. In this regard, by loosening the nut, the rotationalposition of eccentric pin 49 pinched by neutral returning spring 47relative to axis shaft 49 a can be changed to adjust the neutralposition of speed control arm 46 relative to the neutral position ofmovable swash plate 44.

Reduction gear train 70 disposed in gear chamber 10 b will now bedescribed.

Referring to FIG. 6, a laterally horizontal intermediate gear shaft 72is disposed in gear chamber 10 b. Upper housing 11 is formed with rightand left support portions 11 i that journal right and left ends ofintermediate gear shaft 72. A bevel gear 73 is formed with a spur pinion74, and is fixed on intermediate gear shaft 72. Bevel gear 73 mesheswith a bevel pinion 71 fixed on an upper portion of motor shaft 51.

Referring to FIG. 4, a spur bull gear 77 is fixed on right axle 2Rsupported by upper housing 11 and meshes with spur pinion 74. Therefore,bevel pinion 71, bevel gear 73, spur pinion 74 and spur bull gear 77constitute reduction gear train 70 for transmitting power from motorshaft 51 of HST 20 to right axle 2R.

Referring to FIG. 7, intermediate gear shaft 72 is pivotally supportedby upper housing 11 via right and left bearings 72 a and 72 b fixed inrespective right and left support portions 11 i of upper housing 11 soas to be rotatable relative to transaxle casing 10. Referring to FIG.10, bearing covers 75 are fastened to respective support portions 11 iof upper housing 11 by bolts 76 so as to cover top portions ofrespective bearings 72 a and 72 b.

Referring to FIG. 4, a discoid magnet 66 is disposed in gear chamber 10b below a later-discussed brake operation shaft 79, and is supported byupper and lower housings 11 and 12 joined to each other so as to adsorbiron powder mixed in fluid in gear chamber 10 b.

A defoaming pipe 61 is extended in the fore-and-aft horizontaldirection, and is interposed between an upper portion of the frontportion of upper housing 11 defining HST chamber 10 a and a frontportion of top cover 13 defining gear chamber 10 b. A front end portionof defoaming pipe 61 is bent to extend vertically downward, and isfitted into a vertical hole of a boss 11 f formed at a rear portion ofpump shaft support portion 11 b of upper housing 11, so that adownwardly open front end of defoaming pipe 61 is open to the upperportion of HST chamber 10 a. A rear end portion of defoaming pipe 61 isfitted into a fore-and-aft horizontal hole of a boss 13 b formed at afront portion of top cover 13, so that a rearwardly open rear end ofdefoaming pipe 61 is open to the upper portion of gear chamber 10 b.Therefore, air foam rising in the fluid in HST chamber 10 a isintroduced into defoaming pipe 61 and is moved from HST chamber 10 a togear chamber 10 b via defoaming pipe 61.

A top portion of top cover 13 is provided with a breather 62 forbreathing an air space in gear chamber 10 b to the atmosphere. In theupper portion of gear chamber 10 b in top cover 13, a horizontalpartition plate 63 is settled just below breather 62 so as to preventfluid splashed up by the gears of reduction gear train 70 from enteringbreather 62. A metal plate serves as partition plate 63, for example.Partition plate 63 is formed with notches 63 a at front and rear edges,and ribs 13 c formed on top cover 13 to define passages for air andfluid between gear chamber 10 b and breather 62 are fittingly passedthrough front and rear notches 63 a of partition plate 63.

A parking brake 69 of right transaxle 1R will now be described.

Referring to FIG. 8, motor support member 56 is formed with a rearwardlyupward slant through hole 56 a. A bearing 51 a is fitted in hole 56 a.The upper portion of motor shaft 51 projecting rearwardly upward frommotor cylinder block 52 is passed through movable swish plate 54 and isjournalled by motor support member 56 via bearing 51 a.

Motor support member 56 is formed with a flat surface 56 b perpendicularto motor shaft 51. Bevel pinion 71 is fixed on the tip portion of motorshaft 51. More specifically, bevel pinion 71 is spline-fitted on the tipportion of motor shaft 51, and a circular clip 51 b is engaged on thetip portion of motor shaft 51 so as to locate bevel pinion 71.

An annular brake surface member 59 a is fitted on flat surface 56 b ofmotor support member 56, and is partly extended onto an upper surface ofmotor support member 56. Brake discs 58 are disposed parallel to brakesurface member 59 a, and are engaged with teeth of bevel pinion 71 so asto be unrotatable relative to bevel pinion 71 and so as to be slidableon bevel pinion 71 in the axial direction of motor shaft 51.Plate-shaped retainers 59 b as many as brake discs 58 are layeredalternately with brake discs 58, and are fixed to the upper surface ofmotor support member 56. Retainers 59 b are bent to extend parallel tobrake discs 58 so as to be layered alternately with brake discs 58,thereby restricting the slidable range of brake discs 58. Outermostretainer 59 b prevents brake discs 58 from moving to disengage frombevel pinion 71.

Referring to FIG. 7, right and left symmetric shaft holes 11 j areformed through right and left side walls of upper housing 11, andlaterally horizontal brake operation shaft 79 is pivotally supported atright and left end portions thereof through right and left shaft holes11 j rotatably relative to upper housing 11. The left end of brakeoperation shaft 79 projecting outward from upper housing 11 is selectedto have a parking brake arm 78 fixed thereon. More specifically, brakeoperation shaft 79 has the end portion projecting outward from theproximal side surface of transaxle casing 10 opposite the distal sidesurface of transaxle casing 10 from which right axle 2R projectsoutward. Parking brake arm 78 is disposed in the proximal outside oftransaxle casing 10 and is connected to the projecting end portion ofbrake operation shaft 79 pivotally on the axis of brake operation shaft79.

Referring to FIG. 3, in gear chamber 10 b, when viewed in side, atriangular space is provided between rearwardly upward extendedhydraulic motor 50 and bull gear 77, and is used to locate brakeoperation shaft 79 and a pressure arm 80. In gear chamber 10 b, pressurearm 80 is fixed on brake operation shaft 79. A tip portion of pressurearm 80 is formed with a pawl 80 a to be pressed against brake discs 58.When parking brake arm 78 is located at an unbraking position, pawl 80 ais separated from brake discs 58. When parking brake arm 78 is locatedat a braking position, as shown in FIG. 8, pawl 80 a is pressed againstbrake discs 58 so as to press brake discs 58 against surfaces ofretainers 59 b and brake surface member 59 a, thereby braking bevelpinion 71 together with brake discs 58.

Referring to FIG. 1, as mentioned above, vehicle 100 is provided withparking brake control mechanism 169 configured to rotate parking brakearms 78 of right and left transaxles 1R and 1L according to operation ofparking brake pedal 64. Parking brake control mechanism 169 will now bedescribed in detail. As shown in FIG. 1, each of right and left linkrods 19R and 19L has a front end serving as a starting end 19 a, and hasa rear end serving as a terminal end 19 b. Starting ends 19 a of rightand left link rods 19R and 19L are connected to parking brake pedal 64.

Referring to FIG. 1, while right and left axles 2R and 2L of respectiveright and left transaxles 1R and 1L are disposed coaxially to eachother, terminal ends 19 b of respective link rods 19R and 19L arelocated at different positions in the fore-and-aft direction of vehicle100 so as to be connected to respective right and left transaxles 1R and1L. More specifically, terminal end 19 b of right link rod 19R isdisposed forward from terminal end 19 b of left link rod 19L.

Now, left transaxle 1L having parking brake arm 78 connected to leftlink rod 19L will be described with reference to FIG. 11. Left transaxle1L includes parking brake arm 78 fixed on the right end portion of brakeoperation shaft 79 projecting rightward from the proximal right sidesurface of transaxle casing 10. In this regard, parking brake arm 78 isformed in a basal end portion thereof with a pivot hole 78 a, into whichthe proximal right end portion of brake operation shaft 79 is insertedfixedly (i.e., unrotatably relative to parking brake arm 78). Parkingbrake arm 78 of left transaxle 1L is extended upward from its basal endportion provided on the right end portion of brake operation shaft 79 soas to have an upper end portion formed with a connection hole 78 b, intowhich terminal end 19 b of left link rod 19L is fitted pivotally (i.e.,rotatably relative to parking brake arm 78).

In this regard, as mentioned above, tension pulley 91 is disposed at theproximal right side of the proximal right side surface of transaxlecasing 10 of left transaxle 1L adjacently to left transaxle 1L, however,it cannot happen that tension pulley 91 approaches transaxle casing 10of left transaxle 1L so as to interfere with left link rod 19L, becausetension pulley 91 that is fixed in location except for its rotatabilityaccording to driving belt 7 does not come to intersect left link rod19L. Therefore, left transaxle 1L employs the ordinary way for itsconnection to left link rod 19L so that terminal end 19 b of left linkrod 19L is connected to the upper end portion of parking brake arm 78extended upward from its basal end portion fixed on the end of brakeoperation shaft 79.

When parking brake pedal 64 is depressed, left link rod 19L is pulledtogether with right link rod 19R forward so as to rotate the upper endportion of parking brake arm 78 of left transaxle 1L forward, therebycausing brake operation shaft 79 to rotate clockwise as designated by anarrow B1 when the proximal right side surface of transaxle casing 10 ofleft transaxle 1L is viewed as shown in FIG. 11, i.e., counterclockwisein the left side view of left transaxle 1L. This rotation of brakeoperation shaft 79 causes pressure arm 80 to rotate so as to press pawl80 a against brake discs 58, thereby braking left axle 2L of lefttransaxle 1L.

On the contrary, right transaxle 1R having parking brake arm 78connected to right link rod 19R via a relay arm 81 and a link rod 83will be described. As mentioned above, vehicle 100 includes tensionclutch pulley 92 disposed adjacently at the proximal left side oftransaxle casing 10 of right transaxle 1R. When pulley 92 is operatedfor disengaging the tension clutch, pulley 92 approaches the proximalleft side surface of transaxle casing 10 of right transaxle 1R. In thisstate, if right link rod 19R were operatively connected to righttransaxle 1R in the same way as the connection of left link rod 19L toleft transaxle 1L, i.e., if parking brake arm 78 of right transaxle 1Rwere extended upward from brake operation shaft 79, and right link rod19R were directly connected at terminal end 19 b thereof to the upperend portion of parking brake arm 78, link rod 19R would interfere withpulley 92 operated for disengaging the tension clutch.

To avoid the interference of tension clutch pulley 92 with a link rodconnected to parking brake arm 78, first, parking brake arm 78 of righttransaxle 1R is extended downward from brake operation shaft 79 so as tohave a link rod connected to a lower end portion thereof via connectionhole 78 b below pulley 92. More specifically, parking brake arm 78 ofright transaxle 1R is identical to above-mentioned parking brake arm 78of left transaxle 1L. The proximal left end portion of brake operationshaft 79 projecting from the proximal left side surface of transaxlecasing 10 of right transaxle 1R is fixedly inserted into pivot hole 78 ain the basal end portion of parking brake arm 78 of right transaxle 1R.Parking brake arm 78 of right transaxle 1R is extended downward from thebasal end portion thereof provided on the left end portion brakeoperation shaft 79 so as to have connection hole 78 b in its lower endportion.

Therefore, in each of transaxles 1R and 1L, parking brake arm 78 isunrotatable relative to brake operation shaft 79 and is rotatablerelative to transaxle casing 10. Referring to FIGS. 4, 9 and 11, parkingbrake arm 78 has a pivotal axis P5 coinciding to the axis of brakeoperation shaft 79, and parking brake arm 78 is interlocked with brakeoperation shaft 79 so that rotation of parking brake arm 78 causesrotation of brake operation shaft 79. Incidentally, parking brake arm 78may not be completely fixed to brake operation shaft 79, i.e., parkingbrake arm 78 may have a play range for rotation relative to brakeoperation shaft 79, only if pivotal axis P5 of parking brake arm 78coinciding to the axis of brake operation shaft 79 is ensured and therotation of parking brake arm 78 out of the rotational play range causesrotation of brake operation shaft 79.

For the above-mentioned purpose of preventing brake arm 78 or a link rodconnected to brake arm 78 from interfering with other members in vehicle100, it may be conceivable that parking brake arm 78 is extendeddownward and right link rod 19R is directly connected to the lower endportion of parking brake arm 78 of right transaxle 1R. However, itcauses another problem that the rotational direction of brake operationshaft 79 according to depression of parking brake pedal 64 comesopposite its proper rotational direction for applying the parking brake.In this regard, as understood from the description about rotation ofbrake operation shaft 79 of left transaxle 1L, the proper rotationaldirection of brake operation shaft 79 for activating parking brake 69for braking motor shaft 51 is counterclockwise in the left side view ofeach transaxle 1R or 1L. On the contrary, since link rod 19R is pulledforward together with link rod 19L according to the depression ofparking brake pedal 64, brake operation shaft 79 would rotate clockwisein the left side view of right transaxle 1R, i.e., opposite the properdirection for applying the parking brake, according to the forwardmovement of right link rod 19R by depressing parking brake pedal 64, ifterminal end 19 b of link rod 19R were directly connected to the lowerend portion of parking brake arm 78 extended downward from brakeoperation shaft 79.

Therefore, to match the rotational direction of brake operation shaft 79according to depression of parking brake pedal 64 with its properrotational direction for applying the parking brake, parking brakecontrol mechanism 169 includes relay arm 81 and link rod 83 interposedbetween right link rod 19R and the lower end portion of downwardlyextended parking brake arm 78 of right transaxle 1R, as shown in FIGS.1, 2, 4, 7, 9 and 10. Incidentally, it should be noticed that link rod83 is omitted in FIG. 1 just for convenience in illustration.

Relay arm 81 is extended substantially vertically, and is pivoted at thevertical intermediate portion thereof on a pivotal axis provided on theproximal left side of transaxle casing 10 of right transaxle 1R so as tohave upper and lower ends opposite each other with respect to thepivotal axis of relay arm 81. Relay arm 81 includes an upper arm portion81 a extended upward from the pivotal axis to the upper end of relay arm81 so as to have an upper end portion connected to link rod 19R. Relayarm 81 includes a lower arm portion 81 b extended downward from thepivotal axis to the lower end of relay arm 81 so as to have a lower endportion connected to link rod 83, so that link rod 83 is interposedbetween the lower end portion of relay arm 81 and the lower end portionof parking brake arm 78 of right transaxle 1R, so that link rod 83 isdisposed below tension clutch pulley 92 safely from interfering withpulley 92. Relay arm 81 functions to convert the forward movement (asdesignated by an arrow B0 in FIG. 9) of right link rod 19R connected atits terminal end 19 b to the upper end portion of relay arm 81 accordingto depression of parking brake pedal 64 into the rearward movement oflink rod 83 interposed between the lower end portion of relay arm 81 andthe lower end portion of parking brake arm 78. As a result, when parkingbrake pedal 64 is depressed, link rod 83 connected at its terminal end83 b to the lower end portion of parking brake arm 78 is moved rearwardso as to rotate brake operation shaft 79 counterclockwise in the leftside view (as designated by arrow B1 in FIG. 9), i.e., in the properrotational direction to apply parking brake 69 of right transaxle 1R.

As mentioned above, link rod 83 is disposed below pulley 92 to avoid itsinterference with pulley 92. On the other hand, to prevent relay arm 81from interfering with tension clutch pulley 92, relay arm 81 may bedisposed at any position on the proximal left side of transaxle casing10 of right transaxle 1R forward from pulley 92. For example, a lateralhorizontal pivot shaft other than trunnion shafts 45 of movable swashplate 44 may be supported at a front end portion of transaxle casing 10so as to have relay arm 81 pivoted thereon, or relay arm 81 may bepivoted on a projection formed on transaxle casing 10 (e.g., upperhousing 11). However, in this embodiment, left trunnion shaft 45 servesas a relay shaft for pivoting relay arm 81 thereon in consideration ofthe convenience of the left end portion of left trunnion shaft 45, whichis left without speed control arm 46 thereon, and which is disposedforward from pulley 92 appropriately to avoid interference with pulley92.

In this regard, relay arm 81 is provided on the left end portion of lefttrunnion shaft 45 projecting leftwardly outward from the proximal leftside surface of upper housing 11, while speed control arm 46 is providedon the right end portion of right trunnion shaft 45 projectingrightwardly outward from the distal right side surface of upper housing11. Relay arm 81 is formed in the intermediate portion thereof with apivot hole 81 c. The left end portion of left trunnion shaft 45 ispassed through pivot hole 81 c. Relay arm 81 provided on left trunnionshaft 45 is formed with an upper connection hole 81 d in the upperportion of upper arm portion 81 a extended upward from pivot hole 81 c,and is formed with a lower connection hole 81 e in the lower end portionof lower arm portion 81 b extended downward from pivot hole 81 c. Acircular clip 82 is engaged on the left end portion of left trunnionshaft 45 at the proximal outside of relay arm 81 so as to prevent relayarm 81 falling from left trunnion shaft 45, however, so as to allowrelay arm 81 to rotate relative to trunnion shafts 45 of movable swashplate 44. In other words, relay arm 81 has a pivotal axis P1 coincidingto the axis of trunnion shaft 45, i.e., the axis of trunnion shaft 45serves as pivotal axis P1 for relay arm 81, however, relay arm 81 is notfixed to trunnion shaft 45, so that rotation of relay arm 81 does notcause rotation of trunnion shafts 45.

Referring to FIG. 2, terminal end 19 b of right link rod 19R is bentdistally, i.e., rightward, toward transaxle casing 10 and is fitted intoconnection hole 81 d in the upper end portion of relay arm 81. Terminalend 19 b of link rod 19R has a pivotal axis P2 coinciding to a centralaxis of connection hole 81 d. In other words, terminal end 19 b of linkrod 19R and the upper end portion of relay arm 81 are connected to eachother so that they are centered on pivotal axis P2 rotatably relative toeach other. In this regard, right link rod 19R has the fore-and-aftlength between its starting and terminal ends 19 a and 19 b, which isshorter than that of left link rod 19L, so that terminal end 19 b ofright link rod 19R connected to the upper end portion of relay arm 81 isdisposed forward from terminal end 19 b of left link rod 19L connectedto the upper end portion of parking brake arm 78, as mentioned above.

Link rod 83 interposed between relay arm 81 and parking brake arm 78 isextended substantially in the fore-and-aft direction of vehicle 100 soas to have a front end serving as a starting end 83 a and a rear endserving as a terminal end 83 b. Referring to FIG. 2, link rod 83 is bentat starting and terminal ends 83 a and 83 b distally (i.e., rightward)toward transaxie casing 10, so that starting end 83 a of link rod 83 isfitted into connection hole 81 e in the lower end portion of relay arm81, and terminal end 83 b of link rod 83 is fitted into connection hole78 b in the lower end portion of parking brake arm 78. Starting end 83 aof link rod 83 has a pivotal axis P3 coinciding to a central axis ofconnection hole 81 e. In other words, starting end 83 a of link rod 83and the lower end portion of relay arm 81 are connected to each other sothat they are centered on pivotal axis P3 rotatably relative to eachother. Terminal end 83 b of link rod 83 has a pivotal axis P4 coincidingto a central axis of connection hole 78 b. In other words, terminal end83 b of link rod 83 and the lower end portion of parking brake arm 78are connected to each other so that they are centered on pivotal axis P4rotatably relative to each other.

The dimension of upper arm portion 81 a of relay arm 81 is determined soas to have a distance D1 from pivotal axis P1 to pivotal axis P2. Thedimension of lower arm portion 81 b of relay arm 81 is determined so asto have a distance D2 from pivotal axis P1 to pivotal axis P3. The upperarm portion of relay arm 81 is shorter than the lower arm portion ofrelay arm 81 so that distance D1 is less than distance D2. Thisdimension setting of relay arm 81 having the difference betweendistances D1 and D2 corresponds to the difference between the length oflink rod 19R from starting end 19 a to terminal end 19 b and the lengthof link rod 83 from starting end 83 a to terminal end 83 b. Due to smalldistance D1, the movement of link rod 19R and upper arm portion 81 a ofrelay arm 81 upwardly extended from trunnion shaft 15 is reduced so asto avoid their interference with pulley 92 rearward disposed therefrom,and on the other hand, due to large distance D2, the movement of linkrod 83 and the rotation of parking brake arm 78 for applying parkingbrake 69 are enhanced efficiently relative to the reduced movement oflink rod 19R.

In this way, each of transaxles 1R and 1L can be selectively designed tohave parking brake arm 78 extended either upward or downward from brakeoperation shaft 79, and correspondingly, it can be selectively designedto have either a long link rod, such as foresaid left link rod 19L,directly connected at its terminal end to parking brake arm 78, ifparking brake arm 78 is extended upward, or a short link rod, such asforesaid right link rod 19R, connected at its terminal end via relay arm81 and link rod 83 to parking brake arm 78, if parking brake arm 78 isextended downward.

Description will be given of a mechanism for locating speed control arm46 of representative right transaxle 1R with reference to FIGS. 1 and 12to 15. Description of that of left transaxle 1L is omitted on theassumption that right and left transaxles 1R and 1L are symmetric asmentioned above. Trunnion shaft 45 and speed control arm 46, especially,their rotational directions, are referred to on the assumption that theyappear in the right side view of right transaxle 1R as shown in FIGS. 12to 15.

Referring to FIGS. 1, 12, 13 and 14, description will be given of therotational range of speed control arm 46 corresponding to the operationrange of control lever 60R for forwardly rotating corresponding axle 2Rand drive wheel 3R. As mentioned above, the rear end of link rod 18 isfitted into connection hole 46 c in the upper end portion of speedcontrol arm 46, thereby operatively connecting speed control arm 46 ofright transaxle 1R to right control lever 60R via right link, rod 18.Therefore, when right control lever 60R is rotated, right link rod 18 ispulled forward or pushed rearward, so that speed control arm 46 isrotated together with trunnion shafts 45 of movable swash plate 44 inright transaxle 1R. The rotation of speed control arm 46 and trunnionshafts 45 is centered on pivotal axis P1 that also serves as the pivotalaxis for rotation of relay arm 81 relative to transaxle casing 10 ofright transaxle 1R as mentioned above.

Referring to FIGS. 13 and 14, as control lever 60R is rotated forwardfrom its neutral position for forwardly rotating right axle 2R, rightlink rod 18 moves rearward to rotate speed control arm 46counterclockwise around pivotal axis P1 so as to increase fluid inquantity delivered from hydraulic pump 40 in the direction for drivinghydraulic motor 50 for forward rotation of axle 2R. During thiscounterclockwise rotation of speed control arm 46, as understood fromFIG. 14, pressure plate 46 b moves downward so as to push lower endportion El of neutral return spring 47 downward while upper end portionEu of neutral return spring 47 is retained by eccentric pin 49 so as tobe hindered from moving downward to follow lower end portion El, therebygenerating the force of neutral return spring 47 to bias lower endportion El upward toward upper end portion Eu so as to bias speedcontrol arm 46 toward its neutral position N where upper and lower endportions Eu and El of neutral return spring 47 pinch pressure plate 46 btherebetween (see FIGS. 12 and 13). Accurately, the force of neutralreturn spring 47 biases speed control arm 46 toward a later-discussedpredetermined angle T1, however, until predetermined angle T1 isdiscussed, the force of neutral return spring 47 is temporarily definedas biasing speed control arm 46 toward neutral position N for theconvenience of description.

Therefore, if an operator releases right control lever 60R from theoperator's hand after right control lever 60R reaches a target speed setposition in the forward rotational direction from its neutral position,speed control arm 46, having reached an angle (e.g., a maximum angle T2as shown in FIG. 14) corresponding to the speed set position of rightcontrol lever 60R, is automatically returned to neutral position N bythe spring force of neutral return spring 47 so that right control lever60 k automatically returns to its neutral position. This mechanism toautomatically return speed control arm 46 and control lever 60Radvantageously lightens the operator's loads in manipulation forreducing the traveling speed of right drive wheel 3R, and ensures safeand prompt speed reduction of drive wheel 3R in response to anoperator's manipulation. Left transaxle 1L, left link rod 18 and leftcontrol lever 60L are provided with the same mechanism for returningspeed control arm 46 to neutral position N.

However, conversely, the force of neutral return spring 47 biasing speedcontrol arm 46 toward neutral position N means that the operator has tokeep applying a force with the operator's hand to corresponding controllever 60R or 60L against the spring force of neutral return spring 47.In other words, the operator has to endure the resistance of controllever 60R or 60L against the operator's manipulation force, if theoperator wants to keep the rotational speed of drive wheel 3R or 3Lrealized by locating control lever 60R or 60L at the corresponding speedset position.

During a normal on-road travel of vehicle 100, such a resistance ofcontrol lever 60R or 60L against the operator's manipulation force doesnot become a problem because the operator often rotates each of controllevers 60R and 60L to change the rotational speed and direction ofcorresponding drive wheel 3R or 3L. In this traveling state of vehicle100, the average speed of drive wheels 3R and 3L is rather high. On thecontrary, a typical case where the problem occurs is that the lawn mowerserving as vehicle 100 travels for a long time at a relatively low speedappropriate for mowing the lawn. During such a travel of vehicle 100,the operator has to hold right and left control levers 60R and 60L atrespective determined speed positions against the resistances of controllevers 60R and 60L.

Therefore, speed control arm 46 is configured on as to have a smallrotational angle range where its rotation does not generate the springforce of neutral return spring 47 biasing speed control arm 46 towardneutral position N. In this regard, actually, speed control arm 46located at its proper neutral position N accurately corresponding to theneutral position of movable swash plate 44 of hydraulic pump 40 is asshown in FIG. 12, where eccentric pin 49 abuts at the lower end thereofagainst lower end portion El of neutral return spring 47, and isseparated at the upper end thereof from upper end portion Eu of neutralreturn spring 47 thereabove, while upper and lower end portions Eu andEl of neutral return spring 47 has a gap therebetween to pinch pressureplate 46 b therebetween, i.e., to make upper and lower ends of pressureplate 46 b abut against upper and lower end portions Eu and El ofneutral return spring 47.

Referring to FIGS. 12 and 13, as speed control arm 46 is rotatedcounterclockwise from neutral position N, tower end portion El ofneutral return spring 47 is pushed downward by pressure plate 46 b awayfrom the lower end of eccentric pin 49, and upper end portion Eu ofneutral return spring 47 tending to keep the gap between upper and lowerend portions Eu and El of neutral return spring 47 to pinch pressureplate 46 b therebetween follows the downward movement of lower endportion El of neutral return spring 47 so as to approach the upper endof eccentric pin 49. When speed control arm 46 rotating counterclockwisefrom neutral position N reaches a predetermined angle T1, upper endportion Eu of neutral return spring 47 comes to abut against the upperend of eccentric pin 49.

In this way, during the rotation of speed control arm 46 between neutralposition N and predetermined angle T1, the gap between upper and lowerend portions Eu and El of neutral return spring 47 to pinch pressureplate 46 b therebetween is kept, in other words, upper and lower endportions Eu and El of neutral return spring 47 are kept to abut againstthe upper and lower ends of pressure plate 46 b, whereby neutral returnspring 47 does not bias speed control arm 46 toward any position.Therefore, the rotational angle range of speed control arm 46 fromneutral position N to predetermined angle T1 is defined as a dead zonefor neutral return spring 47 in generating its spring force to biasspeed control arm 46 toward proper neutral position N.

In this regard, the technical feature for realizing the rotational anglerange of speed control arm 46 as the dead zone for neutral return spring47 is that the dimension of pressure plate 46 b between its upper andlower ends is set greater than the diameter of eccentric pin 49 (betweenits upper and lower ends) so that upper and lower end portions Eu and Elof neutral return spring 47 pinching pressure plate 46 b therebetweenhas the gap greater than the diameter of eccentric pin 49, therebyspacing at least one of upper and lower end portions Eu and El ofneutral return spring 47 abutting against the upper and lower ends ofpressure plate 46 b from eccentric pin 49. Therefore, the difference ofthe gap between upper and lower end portions Eu and El of neutral returnspring 47 pinching pressure plate 46 b from the diameter of eccentricpin 49 equals the rotational angle range of speed control arm 46 betweenneutral position N and predetermined angle T1.

As far as control lever 60R is located in a low forward traveling speedsetting range to locate speed control arm 46 at any one position in therotational angle between neutral position N and predetermined angle T1,an operator can keep control lever 60R at a set speed position to keepthe constant low speed rotation of corresponding drive wheel 3R freelyfrom the resistance of control lever 60R caused by the spring force ofneutral return spring 47 of right transaxle 1R. Therefore, the low speedsetting ranges of control levers 60R and 60L for setting respectivespeed control arms 46 in the rotational angle ranges between respectiveneutral positions N and respective predetermined angles T1 are availablefor traveling of vehicle 100 at a constant low speed as mentioned above,thereby being advantageous for lightening the operator from fatigue.

When speed control arm 46 is further rotated counterclockwise frompredetermined angle T1 to maximum angle T2, the above-mentioned state ofneutral return spring 47 generating its force biasing speed control arm46 occurs, that is, upper end portion Eu of neutral return spring 47 iskept to abut against eccentric pin 49, and lower end portion El ofneutral return spring 47 is moved downward by pressure plate 46 b sothat the gap between upper and lower end portions Eu and El of neutralreturn spring 47 becomes greater than that to pinch pressure plate 46 btherebetween, thereby generating the spring force of neutral returnspring 47 biasing speed control arm 46 in the clockwise rotationaldirection. Therefore, the middle and high speed setting ranges ofcontrol levers 60R and 60L for setting respective speed control arms 46in the rotational angle ranges between respective predetermined anglesT1 and respective maximum angles T2 are available for the on-roadtraveling of vehicle 100 at various speeds with a relatively high speed.If an operator unexpectedly releases control lever 60R or 60L havingbeen located in the middle and high speed setting range from theoperator's hand, corresponding speed control arm 46 automaticallyreturns to predetermined angle T1 so as to keep the safety in travel ofvehicle 100.

Incidentally, the biasing force neutral return spring 47 for clockwiserotation of speed control arm 46 equals to the upward pressure of lowerend portion El of neutral return spring 47 against the lower end ofpressure plate 46 b. This upward pressure of lower end portion El ofneutral return spring 47 is vanished when the upper end of pressureplate 46 b pushed upward by lower end portion El of neutral returnspring 47 comes to abut against upper end portion Eu of neutral returnspring 47. Pressure plate 46 b abuts against upper end portion Eu whenspeed control arm 46 rotating clockwise reaches predetermined angle T1,Therefore, as mentioned above, the spring force of neutral return spring47 actually functions to bias speed control arm 46 toward predeterminedangle T1 instead of neutral position N. To accurately stop each of drivewheels 3R and 3L, an operator has to consciously rotate correspondingcontrol lever 60R or 60L to its neutral position by the operator's ownmanipulation force so as to set corresponding speed control arm 46 atneutral position N.

Referring to FIGS. 12 and 15, description will be given of therotational range of speed control arm 46 corresponding to the operationrange of control lever 60R for backwardly rotating corresponding axle 2Rand drive wheel 3R.

As control lever 60R is rotated rearward from its neutral position forbackwardly rotating right axle 2R, right link rod 18 moves forward torotate speed control arm 46 clockwise around pivotal axis P1 fromneutral position N to a maximum angle T3 as shown in FIG. 15, therebyincreasing fluid in quantity delivered from hydraulic pump 40 in thedirection for driving hydraulic motor 50 for backward rotation of axle2R. Referring to FIG. 12, as mentioned above, when speed control arm 46is located at neutral position N corresponding to the neutral positionof movable swash plate 44, lower end portion El of neutral return spring47 abuts against the lower end of eccentric pin 49. Therefore, as soonas the clockwise rotation of speed control arm 46 from neutral positionN starts, pressure plate 46 b starts moving upward so as to separate itslower end from lower end portion El of neutral return spring 47 retainedby eccentric pin 49 and so as to push upper end portion Eu of neutralreturn spring 47 upward, so that the gap between upper and lower endportions Eu and El of neutral return spring 47 becomes greater than thatfor pinching pressure plate 46 b, thereby causing the biasing force ofneutral return spring 47 for counterclockwise rotation of speed controlarm 46.

In this way, the clockwise rotation range of speed control arm 46 fromneutral position N to maximum angle T3 in the direction for backwardrotation of axle 2R does not include such a range corresponding to thedead zone of neutral return spring 47 as mentioned above. Therefore, thebiasing force of neutral return spring 47 applied to speed control arm46 operated for backward rotation of axle 2R accurately biases speedcontrol arm 46 toward neutral position N, so that, when control lever60R having been rotated for backward rotation of axle 2R is releasedfrom the operator's manipulation force, control lever 60R automaticallyrotates forward until it reaches its neutral position corresponding toneutral position N of speed control arm 46. In this way, each of controllevers 60R and 60L resists with the force of neutral return spring 47against the operator's manipulation force if it is located at anyposition in its operation range for backward rotation of correspondingdrive wheel 3R or 3L. Therefore, if control levers 60R and 60L havingbeen located in these operation ranges are released from operator'shands, speed control arms 46 of respective transaxles 1R and 1Lautomatically return to respective neutral positions N by the forces ofrespective neutral return springs 47, so that vehicle 100 stopspromptly.

It is further understood by those skilled in the art that the foregoingdescription is given to preferred embodiments of the disclosed apparatusand that various changes and modifications may be made in the inventionwithout departing from the scope thereof defined by the followingclaims.

What is claimed is:
 1. A transaxle comprising: a transaxle casing; anaxle supported by the transaxle casing; a brake, wherein the brakeincludes a brake operation shaft pivotally supported by the transaxlecasing so as to rely on rotation of the brake operation shaft forshifting the brake between an activation state to brake the axle and aninactivation state to unbrake the axle; a brake arm disposed outside ofthe transaxle casing and connected to the brake operation shaftpivotally on an axis of the brake operation shaft so that rotation ofthe brake arm causes the rotation of the brake operation shaft; a firstlink member having a starting end and a terminal end, wherein thestarting end of the first link member is connected to a manipulatoroperated for shifting the brake between the activation state and theinactivation state; a second link member having a starting end and aterminal end, wherein the terminal end of the second link member isconnected to the brake arm; and a relay arm pivotally centered on afirst pivotal axis outside of the transaxle casing, wherein the firstpivotal axis is parallel to the axis of the brake operation shaft,wherein the relay arm includes first and second ends opposite each otherwith respect to the first pivotal axis, a first arm portion extendedfrom the first pivotal axis to the first end, and a second arm portionextended from the first pivotal axis to the second end, wherein theterminal end of the first link member is connected to the first armportion of the relay arm, and wherein the starting end of the secondlink member is connected to the second arm portion of the relay arm. 2.The transaxle according to claim 1, further comprising: a hydrostatictransmission disposed in the transaxle casing, wherein the hydrostatictransmission includes a hydraulic pump and a hydraulic motor fluidlyconnected to each other, wherein the hydraulic pump includes a movableswash plate having a trunnion shaft, and wherein the trunnion shaftprojects outward from the transaxle casing so as to have the relay armpivoted thereon so that a rotary axis of the trunnion shaft serves asthe first pivotal axis.